JP2008176984A - Ion beam processing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion beam processing device capable of correcting abnormalities, if any, or otherwise cutting off causes of abnormalities and preventing itself from being used at an abnormal state, by monitoring if ion beams are normal or abnormal. <P>SOLUTION: With the use of first and second blankers 128, 132, and first and second Faraday cups 130, 134, beam currents are monitored at top and bottom points of a projection mask 115 by changing on-offs of the first and the second blankers 128, 132. With this, while damage of the projection mask 115 is restrained, abnormality information of ion beams is obtained, enabled to cut off causes of abnormalities and correct abnormalities. Thus, a stable processing by ion beams is realized, and the ion beam processing device can be stably used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ion beam processing apparatus that processes a sample for inspection of a device or the like or for failure analysis.

  There is a growing need for inspection and analysis of semiconductor devices that are becoming finer. Among them, in the failure analysis for specifying the cause of the failure, it is an essential technique to directly observe the defects inside the device. For these observations, it is necessary to precisely machine the observation target position of the device. Conventionally, a focused ion beam (hereinafter referred to as FIB) processing apparatus has been used as an apparatus for performing this precise fine processing. In this FIB, the target position can be accurately processed by electrostatic deflection scanning of the ion beam focused on the submicron order and irradiating the sample. Therefore, this FIB is used for forming a cross section for analysis, producing a sample for analysis, etc. .

  Further, in this defect analysis processing, in recent years, the need for preparing an analysis sample in a shorter time is increasing. That is, since the yield improvement is directly linked to the device cost, the identification of the cause of the defect in a short time has a great influence on the cost reduction. For this reason, high-speed analysis sample preparation is expected. As a processing apparatus for realizing this, for example, there is a projection ion beam (hereinafter referred to as PJIB) processing apparatus described in Patent Document 1. This is not done by focusing the ion beam and performing deflection scanning as in the above FIB, but preparing a mask pattern similar to the predetermined target shape and applying this mask pattern on the sample. It is an apparatus that performs batch processing by projecting. The processing speed is generally determined by how many ions are irradiated on the processing area, that is, the higher the ion beam current, the higher the processing speed becomes possible. In a simple ion beam current density at the beam diameter, FIB is larger than PJIB. However, in processing of an area in which PJIB ion beam current is larger than FIB ion beam current, PJIB processing is simply performed. Will be faster. Actually, in the case of processing used for device failure analysis, processing in the sub-micron region is rare, and processing in the region of several to several tens of microns is almost necessary, and in these areas, PJIB There is a merit that processing is faster.

  Failure analysis using these ion beam processing devices has been often used by specialized operators in the past, so even if an abnormal situation occurs in the device, it was possible to cope with the skill of the operator. Since the number of apparatuses capable of automatic processing without an operator has increased, it is particularly important to ensure the stability of the beam in these apparatuses. Monitoring the beam is effective for ensuring the beam stability. For example, Patent Document 2 describes a beam current monitoring method using an ion implantation apparatus as an example. This is done by measuring the current density distribution at two locations before and after the workpiece using a multipoint Faraday cup, and interpolating or extrapolating the current density distribution of the ion beam at the workpiece (sample) position. It is stated that For example, it is described that the beam distribution can be corrected by shortening the scan stay time in a region where the current density is low and shortening the scan stay time in a region where the current density is high, for example.

Japanese Patent No. 3542140 Japanese Patent No. 3556749

  The technique disclosed in Patent Document 2 is effective for minute distributions and fluctuations that can be corrected by beam scanning. For this reason, in the case of FIB, it is considered that correction may be possible, but PJIB generally does not scan and projects a mask shape, so correction by changing the scanning speed is impossible.

  In some cases, the beam is greatly abnormal and cannot be corrected by changing the scanning speed. For example, when the beam deviates from the center of the optical axis due to some influence, the profile of the beam itself may be collapsed, the beam tail may become slack, and the processed shape may be disrupted. Further, since the ion beam damages the component irradiated with the beam in the optical system, there is a possibility that the lifetime of the component will be involved. In this case as well, correction is impossible in the above-described conventional example.

  An example in which the lifetime of the component greatly affects is a PJIB projection mask. Since the projection mask has a function of selectively passing only the ion beam used for sample processing among the irradiated ion beams, the ion beam that is not allowed to pass causes damage due to sputtering of the projection mask itself. However, in PJIB, since the mask pattern shape determines the processing shape, the mask pattern must be prevented from collapsing. In order to extend the lifetime, one solution is to increase the thickness of the mask so that it will last even if it is sputtered. However, if the thickness is increased, there is a problem that a fine pattern cannot be formed due to the problem of processing aspect. For example, if it is desired to form a pattern having a width of 10 μm on the mask, if the mask thickness is 1 mm, the processing aspect ratio is 100, and mask fabrication becomes difficult. For this reason, although it depends on the formation pattern size, the mask thickness generally has an upper limit, for example, about 300 μm. Thus, on the premise that the mask has a lifetime, a function for preventing a sample processing failure due to this is required.

  In the above description, the projection mask of PJIB has been described as an example. However, in the case of FIB as well, it is general to have a movable diaphragm having a plurality of apertures of different sizes for switching the beam current. In this case as well, there is a problem in life because the movable diaphragm is sputtered by the irradiation beam as in the case of the projection mask. If the beam current applied to the sample increases due to the movable aperture reaching the end of its life and increasing the aperture hole diameter, not only the beam current increases, but also the beam profile itself, such as the beam edge, can be destroyed. High nature. In this case, the beam irradiation condition to the sample cannot be corrected only by correcting the beam residence time as in the conventional example. In particular, in the case of FIB used for microfabrication, it is important to prevent the use of such an abnormal state because the beam drift is fatally connected to the processing failure.

  In this way, it is possible to monitor whether the ion beam is normal or abnormal, and if it is abnormal, correct it, or if it cannot be corrected, identify the cause of the abnormality, and provide an ion processing device that can prevent it from being used in an abnormal state It is important to.

  In order to solve these problems, in the present invention, a sample stage for holding a sample, an ion source for generating an ion beam, a plate-like member having an opening, and an opening for the sample held on the sample stage are provided. An ion beam processing system with an irradiation optical system that irradiates the transmitted ion beam. It has a blanker and a beam current detector on the ion source side of the aperture. When the ion beam irradiation to the sample is not required, the blanker is turned on and the beam current is turned on. The current is monitored by a detector.

  In addition, a sample stage for holding a sample, an ion source for generating an ion beam, a plate member having an opening, and an irradiation optical system for irradiating the sample held on the sample stage with an ion beam transmitted through the opening A configuration in which a first blanker and a first beam current detector are installed on the ion source side of the aperture, and a second blanker and a second beam current detector are installed on the sample side of the aperture. And When the ion beam irradiation to the sample is unnecessary, the first blanker is turned on and the current is monitored by the first beam current detector, and the first blanker is turned off immediately before the ion beam irradiation to the sample. The second blanker is turned on and the current is monitored by the second beam current detector.

  According to the present invention, stable operation of an ion beam processing apparatus can be realized, and highly reliable defect analysis can be realized, which can contribute to improvement in yield in a semiconductor process. In particular, by having a blanker and a beam current detector on the ion source side of the aperture, the damage to the projection mask, which is a plate-like member having an aperture, is suppressed, and the stability of the beam current itself irradiated to the aperture is reduced. Since it can be monitored, the abnormality on the ion source side can be grasped from the opening. Further, by installing a second blanker and a second beam current detector on the sample side of the opening, the detailed ion beam state is monitored in cooperation with the first blanker and the first beam current detector. This makes it possible to monitor the stability of the ion beam used for processing of the ion beam processing apparatus while suppressing damage to the projection mask, which is a plate-like member having an opening.

  Hereinafter, specific examples of an ion beam processing apparatus and a processing method capable of realizing stable operation by monitoring an ion beam, correction based on the ion beam, and identification of an abnormality cause will be described with reference to the drawings.

  In this embodiment, the configuration of the PJIB apparatus according to the present invention will be described.

  The PJIB apparatus shown in FIG. 1 has a movable sample stage 102 on which a sample substrate of a sample 101 such as a semiconductor wafer is placed, and a sample position control for controlling the position of the sample stage 102 in order to specify the observation and processing position of the sample 101. The apparatus 103 includes an ion beam optical system 105 that performs processing by irradiating the sample 101 with the ion beam 104, and a secondary electron detector 106 that detects secondary electrons from the sample 101. The secondary electron detector 106 is controlled by a secondary electron detector controller 107. An assist gas source 108 for supplying an assist gas used for ion beam assist deposition or ion beam assist etching is controlled by a gas source controller 109. The probe 110 for extracting a processed sample and measuring electrical characteristics is controlled by a probe controller 111.

  The secondary electron detector control device 107, the gas source control device 109, the sample position control device 103, the probe control device 111, and control devices for each component of the ion beam optical system 105 described later are controlled by the central processing unit 112. Is done. For example, a personal computer or a workstation is generally used as the central processing unit 112 here. In addition, the display device 113 is included. The sample stage 102, the ion beam optical system 105, the secondary electron detector 106, the assist gas source 108, and the like are arranged in a vacuum vessel 114. With this configuration, the ion beam 104 formed by the ion beam optical system 105 is irradiated to the sample 101 placed on the sample table 102 for processing. In this embodiment, the shape of the ion beam 104 is determined by the shape of the opening opened in the projection mask 115.

  Next, details of the ion beam optical system 105 will be described. The ion source 116 generates ions and is controlled by the ion source control device 117. In this embodiment, the case of a plasma ion source is shown. As the plasma ion source, various ion sources such as a duoplasmatron, an inductively coupled plasma ion source, a Penning ion source, and a multicusp ion source can be used. These plasma ion sources are mainly used as ion sources for gas materials such as oxygen, nitrogen, and rare gases. In addition to the plasma ion source, an ionization ion source or the like is also used as an ion source for the gas material. In addition, a liquid metal ion source or the like is also used as an ion source of a material such as a metal, and various ion sources can be used in this apparatus.

  Ions are extracted as an ion beam through an extraction electrode 118. The extracted ion beam is irradiated onto the projection mask 115 through the irradiation lens 120 controlled by the irradiation lens power source 119. The ion beam that has passed through the projection mask is projected onto the sample 101 by the projection lens 122 controlled by the projection lens power supply 121. As a result, the sample is processed into the opening shape of the projection mask 115 reduced at a reduction ratio determined by the conditions of the projection lens 122. Here, the processing position, that is, the irradiation position of the ion beam 104 on the sample is determined by the main deflector 124 controlled by the main deflector controller 123. In general, the main deflector 124 is often an electrostatic deflector that easily deflects ions.

  The projection mask 115 described above is generally composed of a plate-like member having a plurality of types of pattern openings, and the selection of the openings is performed by moving the projection mask 115. This is configured such that a target opening can be selected by sliding in a plane with one or two axes by a projection mask driving mechanism 126 controlled by the projection mask controller 125. In addition to the pattern opening for processing, the projection mask 115 has an observation minute opening (minute hole). In this method, a microscopic aperture is projected onto the sample surface, scanned by the main deflector 124, secondary electrons generated by the scanning are detected by the secondary electron detector 106, and this is imaged on the display device 113 as a contrast signal. By doing so, it is possible to acquire a scanning ion image (Scanning Ion Microscopy image, hereinafter referred to as a SIM image) on the surface of the sample 101. In this case, the image resolution is determined by the size of the minute aperture of the projection mask 115, and the smaller the resolution, the higher the resolution. However, if it is small, the ionic current also decreases, so the S / N becomes worse.

  Here, in order to monitor the ion beam current, a blanker and a Faraday cup are provided in the optical system. FIG. 2 shows the configuration. The Faraday cup 201 generally has a cylindrical shape made of a conductive material as shown in FIG. The measurement principle is as follows. Since the ion beam has a charge, a current corresponding to the charge flows when the conductive member is irradiated. Therefore, the current can be measured by connecting an ammeter to the conductive member. However, when the conductive member is irradiated with an ion beam, an amount of secondary electrons depending on the material of the conductive member, ion beam mass, energy, and the like is emitted from the conductive member. Since the amount of secondary electrons is also measured by an ammeter connected to the conductive member, an accurate ion beam dose cannot be measured. However, although it is not accurate even with a plate-like conductive member, monitoring related to the magnitude of the ion beam current is possible, so it can also be used as a low-cost current monitoring mechanism. On the other hand, a Faraday cup having a shape in which the secondary electrons 202 cannot escape as a deep hole structure as shown in FIG. The amount can be measured by the ammeter 204. As shown in Fig. 2 (a), the closed Faraday cup, which is intended only for current measurement, has no problem with the closed bottom. However, when current measurement is performed in the optical system, the sample must have a structure that can be irradiated with an ion beam. A configuration capable of current measurement and beam passage is desired. A configuration in which a Faraday cup with a closed bottom as shown in FIG. 2A is mechanically inserted into the ion beam optical axis during measurement and removed from the optical axis during sample irradiation is also conceivable. However, in this case, mechanical movement in the optical system is necessary and there is a possibility of dust generation. Therefore, the combined use of Fig. 2 (c) and the blanker shown in Fig. 2 (d), which is a cross-sectional view, is common. Used. A minute hole 206 for passing an ion beam is formed on the bottom surface of the Faraday cup 205. The blanker 207 is often composed of two counter electrodes. When the sample is irradiated with an ion beam, both poles of the blanker 207 are set to be equipotential (generally, it is often a ground potential, hereinafter referred to as turning off the blanker), the ion beam 203 is not deflected, and the Faraday cup Irradiate through 205 holes. On the other hand, when measuring the ion beam current, different voltages are applied to both poles of the blanker 207 (hereinafter referred to as turning on the blanker), the ion beam 203 is shifted from the central axis by electrostatic force, and ions are applied to the bottom surface of the Faraday cup 205. The beam 203 is irradiated. In this way, the ion beam current is measured by the ammeter 208 connected to the Faraday cup 205. Further, since the ion beam 203 is blocked at the bottom surface of the Faraday cup 205 by turning on the blanker 207, it can simultaneously serve as a shield for non-irradiation of the ion beam. Since the minute hole 206 on the bottom of the Faraday cup 205 is generally about 1 mm or more in diameter and larger than the opening of the projection mask 115, the thickness limitation of the projection mask described in the problem to be solved by the invention is as much as possible. Since there is no thickness limitation, it is common to increase the thickness in consideration of the lifetime, but it is still a consumable part because it is always damaged by sputtering. For this reason, in order to extend the life, the voltage polarity applied to the both poles of the blanker 207 is reversed so that the ion beam 203 swings in reverse, or the electrodes are made not only two opposing but also multipole type so that the Faraday cup It is possible to further extend the life by swinging the ion beam 203 to 205 different positions.

  In FIG. 1, the first blanker 128 controlled by the first blanker controller 127 and the first Faraday cup 130 to which the first Faraday cup ammeter 129 is connected are located above the projection mask 115 (on the ion source 116 side). Have. With this configuration, as shown in FIG. 3A, the blanker 128 can be turned on and the projection mask 115 can be prevented from being irradiated when the sample 101 is not irradiated with the ion beam. Accordingly, the projection mask 115 can be prevented from being damaged by the sputtering accompanying the ion beam irradiation, so that the projection mask 115 can be used with a longer life compared to the case where the ion mask is always irradiated with the ion beam. It becomes. Further, with this configuration, the ion beam current can be monitored even when the sample 101 and the projection mask 115 are not irradiated with the ion beam. By doing so, the ion beam current at the normal time is recorded in the central processing unit 112, and it can be determined that there is an abnormality when the ratio changes from the normal value to a preset ratio, for example, 20% or more. The processing at the time of abnormality will be described later.

  Although the current on the projection mask 115 can be monitored by the first blanker 128 and the first Faraday cup 130 described above, the ion beam current actually used for sample processing is transmitted through the projection mask 115. Since it is an ion beam, it is better to monitor the current of the ion beam that has passed through the projection mask 115 in order to determine the processing conditions. For this reason, the second blanker 132 controlled by the second blanker controller 131 and the second Faraday cup 134 connected to the second Faraday cup ammeter 133 are provided below the projection mask 115 (on the sample 101 side). Have. As a result, as shown in FIG. 3B, the ion beam current after passing through the projection mask 115 can be measured as in the case of the first blanker 128 and the Faraday cup 130. Of course, when the ion beam current is monitored using the second Faraday cup 134, it goes without saying that the first blanker 128 is turned off. Further, in order to adjust the ion beam irradiation position of the projection mask 115, a deflector 136 controlled by a deflector controller 135 is provided between the ion source 116 and the projection mask 115. As the main deflector 124, the deflector 136 is generally an electrostatic deflector that easily deflects ions in many cases.

  Here, the area of the opening used for processing in the projection mask 115 and the projection magnification (reduction ratio) on the sample 101 are determined as known ones. More specifically, when the projection lens 122 is a single-stage lens as shown in FIG. 1, the distance between the projection mask 115 and the projection lens 122 and the distance between the projection lens 122 and the surface of the sample 101 are mechanically determined. Thereby, the applied voltage condition of the projection lens 122 is also uniquely determined. As a result, the projection magnification is also uniquely determined. If multiple projections are performed using a plurality of projection lenses, the projection magnification is not uniquely determined only by the mechanical configuration such as the distance between the projection mask 115 and the projection lens. The reduction rate can be determined by determining the application conditions. Considering the use of an actual apparatus, the shape (area) to be processed on the sample 101 is basically determined as a need, and the projection mask 115 is manufactured by determining the reduction ratio and designing the necessary opening of the projection mask 115. In general, the reduction ratio is usually determined at the setting stage of the apparatus. In this embodiment, for example, this projection magnification is 1/10. That is, when it is desired to process the sample 101 with a length of 10 μm, the opening of the projection mask 115 has a length of 100 μm (in the case of non-scanning processing).

ここで、V[m³]は加工体積、I_b2[A]は第２のファラデーカップ１３４で測定されたイオンビーム電流、t[s]は加工時間であり、R[m³/C]は単位電荷当たりの加工体積で以下(数２)の通り表される。

ここで、Sは上記スパッタリング率、Wは試料構成元素の原子量、u(=1.66E-27[kg])は原子質量単位、e(=1.60E-19[C])は電気素量、ｄ[kg/m³]は試料構成元素の密度である。また、(数１)の体積Vは投射マスク開口面積との関係で以下の通り表される。

ここで、A[m²]は投射マスク開口面積、Mは投射倍率、D[m]は加工深さである。即ち加工時間tは下記(数４)で表される。

ここで、積の始めの項(e・M²/u)は装置構成として決まる値となる。積の２番目の項(d /(W・S))は試料材質から決まる値であり、積の３番目の項(A・D)は加工したい形状から決まる値である。このため、これらは加工セッティング時に自明の値となる。積の最後の項(1/ I_b2)はモニタ電流で決まるものであるため、このモニタされた電流から加工時間を自動的に算出することができる。 Further, the processing volume of the sample 101 with respect to the ion beam current is determined as described below. The ion sputtering rate indicating how many atoms in the sample are sputtered when one ion is incident on the sample is the primary ion species, the primary ion acceleration energy, the material constituting the sample, the ion beam It is determined from the incident angle on the sample surface. Since the ion sputtering rate can be obtained if the above parameters are known, the processing volume per unit time can be obtained from the ion beam current. Therefore, if the depth to be processed is determined, the time to be processed, that is, the ion beam irradiation time to the sample can be obtained. Specifically, the calculation method is as follows. First, the volume to be processed is expressed by the following (Equation 1).

Here, V [m ³ ] is the processing volume, I _b2 [A] is the ion beam current measured by the second Faraday cup 134, t [s] is the processing time, and R [m ³ / C] is The processing volume per unit charge is expressed as follows (Equation 2).

Here, S is the sputtering rate, W is the atomic weight of the sample constituent element, u (= 1.66E-27 [kg]) is the atomic mass unit, e (= 1.60E-19 [C]) is the elementary electric charge, d [kg / m ³ ] is the density of the sample constituent elements. Further, the volume V in (Equation 1) is expressed as follows in relation to the projection mask opening area.

Here, A [m ² ] is the projection mask opening area, M is the projection magnification, and D [m] is the processing depth. That is, the processing time t is expressed by the following (Equation 4).

Here, the first term (e · M ² / u) of the product is a value determined as a device configuration. The second term (d / (W · S)) of the product is a value determined from the sample material, and the third term (A · D) of the product is a value determined from the shape to be processed. For this reason, these are self-evident values at the time of machining setting. Since the last term (1 / I _b2 ) of the product is determined by the monitor current, the machining time can be automatically calculated from the monitored current.

The outline of the processing flow in the present embodiment is shown in FIG. As described above, when the sample 101 is not irradiated with the ion beam, the first blanker 128 is turned on to block the beam (401). First, a value of (e · M ² / u) is input to the central processing unit 112 in advance. However, if the projection magnification M is variable with a plurality of projection lenses as described above, this is also a parameter. Next, the material of the sample to be processed is set (402). For this, register (d / (W ・ S)) of materials that may be used in advance, and if you select a material from the pull-down menu, the value of (d / (W ・ S)) is automatically set. It is desirable to set. Next, a shape to be processed is selected from a plurality of openings (403). The opening area of the projection mask 115 is registered in advance in the central processing unit 112, and the area of the selected opening is automatically substituted for A. Further, the processing depth D may be specified by the user, or a template corresponding to the selected opening may be substituted by creating a template for each opening (404). After the above setting is completed, the second blanker 132 is turned on (406). Then, the first blanker 128 is turned off (407) and the projection mask 115 is irradiated with the ion beam, so that the ion beam current I _b2 immediately before the processing sample is irradiated with the second Faraday cup 134 is obtained. Can be measured (408). The machining time t can be calculated by substituting the measured ion beam current I _b2 immediately before the ion beam irradiation into (Equation 4) in this way (409).

  Thereafter, processing positioning is performed by adjusting the deflection voltage (410), and actual processing is started by turning off the second blanker 132 (411), and the first blanker 128 is turned on after t seconds. The machining can be stopped by turning on (412 and 413). In this way, it is possible to perform processing at a desired depth. Although it is possible to turn on the second blanker 132 and shield the beam when the processing is stopped, it is better to shield with the first blanker 128 in terms of suppressing damage to the projection mask 115.

Next, the abnormality handling by the current monitor will be described. The configuration of FIG. 1 can monitor the current of the first Faraday cup 130, that is, the ion beam current on the projection mask 115, and the current of the second Faraday cup 134, that is, the ion beam current that has passed through the opening of the projection mask 115. It is. Here, the current of the first Faraday cup 130 is I _b1, and the current of the second Faraday cup 134 is I _{b2 as} described above. Here, when normal processing is performed, that is, when there is no abnormality in the ion beam optical system 105, the current values I _b10 and I _b20 of the first and second Faraday cups are stored in the memory of the central processing unit 112 in advance. Remember. Incidentally, there is actually a different _Ib20 for each of the plurality of openings of the projection mask 115, but here, in order to simplify the description, description will be made with attention paid to one of the openings. Furthermore, a current value that can be normally used is also set. The upper and lower limits of the current value of the first Faraday cup 130 that can be normally used are I _b1U and I _b1L , respectively. For example, the upper and lower limits may be set on the basis of empirical rules, or may be set in proportion. As an example of setting the ratio, if the normal range is ± 20%, I _b1U = 1.2 I _b10 and I _b1L = 0.8 I _b10 . Similarly, in the case of the second Faraday cup 134, the upper and lower limits of the normal use range are _set to I _b2U and I _b2L , respectively.

As described above, each ion beam current monitor is used to monitor the ion beam stability when the sample is not processed with I _b1 , and monitor the processing parameters with I _b2 . Here, how to deal with each abnormal state of the current monitor will be described below. Here, it is assumed that normal use was possible before these abnormal states, and the abnormal state caused by, for example, replacement of parts of the ion beam optical system 105 at the time of discontinuous use after maintenance, etc. Not assumed. In this case, however, the following countermeasures can be used as a guideline for specifying the abnormal position.

(a) When I _b1 > I _b1U or I _b1 <I _{b1L In} other words, this is a case where a current abnormality occurs above the projection mask 115. In this case, it is the abnormality of the ion source 116 that is considered most likely to be the cause of the abnormality. For example, in the case of the plasma ion source used in the present embodiment, there may be causes such as abnormal pressure of the raw material gas, discharge failure due to contaminants (contamination), ion path interruption, discharge failure due to electrode plasma sputtering, and the like. Of course, there is a possibility of power supply abnormality including other than the ion source 116. For this reason, the following countermeasures can be considered.

(a-1) Warning display As shown in Fig. 5 (a), abnormalities such as "Projection mask irradiation current abnormality", "Ion source side current abnormality" and "Please contact the call center for abnormality" on the display device 113 A display 501 is displayed. Along with this, machining failure can be prevented by locking the machining start button or the like. A square frame in the display device 113 indicates an observation image display area. Further, as shown in FIG. 5B, a schematic configuration 502 of the device is displayed on the display device 113, and an abnormal portion therein, for example, in the case of this example, the region 503 on the ion source side of the projection mask is blinked or highlighted. By showing the abnormality so as to be understood by, for example, the user can easily understand the abnormal part. Further, it is also possible to output the abnormality and the abnormal part as the abnormality information by using a buzzer or a voice synthesis technique to notify the user of the abnormality. Further, when the central processing unit 112 is connected to the Internet, it is also possible to transmit abnormality information to the device manufacturer via the Internet and request a service engineer's response. All of these can be called output units that output abnormality information.

(a-2) Corresponding Manual Display A user response flow 601 for returning from an abnormality as shown in FIG. 6 is displayed on the display device 113. The order of the display items is related to a portion having a high possibility of anomaly, and it is more efficient that the user can easily investigate. In the case of this example, for example, the following question 602 is displayed on the display device. “Is the gas pressure normal?” In response to this, pressing the “Yes” or “No” button 603 causes the next option to be displayed. In case of “No”, “Please adjust the gas pressure within the normal value” is displayed. If yes, go to the next adjustment. Here, for example, “adjust the extraction electrode position and adjust the ion beam current to the maximum value” is displayed. In this example, the position of the extraction electrode 118 is mechanically adjustable from the atmosphere. These adjustable items are sequentially displayed on the screen. When there are no items that can be adjusted, display a maintenance procedure that requires opening the atmosphere, such as “Replace the cathode of the ion source”.

(a-3) Automatic correction First, the central processing unit 112 determines whether all optical parameters that can be monitored are within the normal range. For example, these are the degree of vacuum of the ion beam optical system 105, the plasma discharge power supply voltage, the ion acceleration voltage, the irradiation lens power supply voltage, and the like. If they are out of the normal range, they are first corrected to normal values and the ion beam current _Ib1 is monitored again. These processes are automatically performed by the central processing unit 112. If the ion beam current returns to the normal value, there is no problem. However, if the ion beam current does not return to the normal value, correction is attempted using other adjustable parameters. For example, a correction example with the plasma ion source configuration used in this embodiment is shown below. FIG. 7 shows a configuration of a duoplasmatron, which includes a cathode 701, an intermediate electrode 702, a magnet 703, an anode 704, a control electrode 705, and an extraction electrode 118. Here, Vd is a discharge voltage, Vb is a control voltage, and Va is an acceleration voltage. Among these, the acceleration voltage Va determines the energy of the ion beam, and therefore is not generally used as a correction parameter. The optimum value of the discharge voltage Vd varies depending on the gas pressure, etc., but it is generally unnecessary to change the discharge voltage if the gas pressure is normal, and conversely, the discharge voltage must be changed. Since this means that the plasma itself is not in an appropriate state, correction by the discharge voltage is also less desirable. As a parameter that can be corrected without changing ion energy or plasma state in this way, there is a control voltage Vb. Therefore, while monitoring the ion beam current I _b1 , the control voltage Vb is applied by the central processing unit 112, and the control voltage Vb is set so that the ion beam current I _b1 falls within the normal range I _b1U > I _b1 > I _b1L. It can be corrected by setting. In addition to the control voltage Vb, correction may be possible by shaking the deflector 136. However, if the correction cannot be made due to these, the above (a-1), (a-2), etc. are taken.

  With the above measures, it is possible to realize processing failure suppression and correction when the ion beam above the projection mask is abnormal.

(b) When I _b1U > I _b1 > I _b1L and I _b2 > I _b2U That is, the current value above the projection mask 115 is normal, but the ion beam current passing through the projection mask 115 increases. is there. In this case, it is the damage of the projection mask 115 that is considered most likely to be an abnormal cause. That is, it is considered that the projection mask 115 is sputtered by the ion beam and the opening becomes large. For this reason, the following countermeasures can be considered.

(b-1) Warning display Similar to (a-1), the display device 113 shows an abnormality such as “projection mask abnormality” or “please contact the call center for abnormality” as shown in FIG. 5 (a). Display. Along with this, machining failure can be prevented by locking the machining start button or the like. Further, as in FIG. 5 (b) in (a-1), the schematic configuration of the apparatus is displayed on the display device 113, and an abnormal portion therein, for example, in this example, the projection mask is abnormal due to blinking or highlighting. The user can easily understand the abnormal part by transmitting the sound information using a voice synthesis technique. In addition, as described above, when the central processing unit 112 is connected to the Internet, it is possible to transmit abnormality information to the device manufacturer via the Internet and request a service engineer's response.

(b-2) Corresponding manual display The user's corresponding flow for returning from an abnormality is displayed on the display device 113 in the same manner as in FIG. 6 of (a-2). In the case of this example, how to replace the projection mask is displayed on the screen. For example, the power of the ion beam optical system element is turned off, the evacuation system of the ion beam optical system is stopped, the ion beam optical system 105 is opened to the atmosphere, and the projection mask 115 is replaced.

(b-3) Automatic correction In order to determine whether or not the projection mask 115 damage is a sure cause as described above, another opening (here, the opening A) different from the opening where the abnormality was found (here, the opening A) is used. The projection mask position is switched to the aperture B, and it is monitored whether the passing current (second Faraday cup 134 current) of the aperture B is within the normal value range of the aperture B. This uses the fact that the frequency of use is different for each opening, so that the possibility of the opening becoming large at the same time due to damage is low. That is, if the passing current of the opening A is abnormal but the passing current of the opening B is normal, it can be confirmed that only the opening A is damaged. Here, if a projection mask 115 having a plurality of openings having the same shape as the opening A (for example, having an opening A ′) is used, the central processing unit 112 controls the projection mask drive mechanism 126 from the projection mask controller 125. The use of the opening A is prohibited by controlling and the automatic switching to use the alternative opening A ′ enables normal use.

  As described above, processing failure due to damage to the projection mask can be suppressed.

(c) When I _b1U > I _b1 > I _b1L and I _b2 <I _b2L That is, this is a case where the current value above the projection mask 115 is normal, but the ion beam current passing through the projection mask 115 decreases. is there. In this case, it is the deviation of the irradiation beam 802 to the opening 801 of the projection mask 115 as shown in FIG. That is, the absolute value of the irradiation current to the projection mask 115 does not change, but the ion beam is not normally irradiated to the opening. For this reason, the following countermeasures can be considered.

(c-1) Warning display As in (a-1) and (b-1), a display indicating an abnormality such as “irradiation to the projection mask” is displayed on the display device 113 as shown in FIG. Along with this, machining failure can be prevented by locking the machining start button or the like. Similarly to (a-1) and (b-1), as shown in FIG. 5 (b), the schematic configuration of the apparatus is displayed on the display device 113, and an abnormal part therein, for example, a projection mask in this example, is displayed. By displaying the beam shift to the point so that the abnormality can be recognized by blinking, highlighting, etc., the user can easily understand the abnormal part.

(c-2) Corresponding manual display The user's corresponding flow for recovery from an abnormality is displayed on the display device 113 in the same manner as FIG. 6 of (a-2) and (b-2). In this example, the deflector 136 is adjusted, the position of the extraction electrode 118 is adjusted, and the like.

(c-3) Automatic correction 1
Among the apparatus configurations that can change the ion beam irradiation position onto the projection mask 115, a deflector 136 is controllable from the central processing unit 112. For this reason, in some cases, the central processing unit 112 can monitor the ion beam current I _b2 , and shake the deflector 136 to set the deflector 136 voltage at the maximum position to automatically correct the ion beam current I _b2 . As the opening used at this time, a simple central symmetry of the opening is desirable. For example, the openings 901 to 905 such as a circle as shown in FIG. As shown in FIG. 10, when the profile of the irradiation ion beam 1001 has a high density near the center 1002 and a thin periphery, for example, in the case of a U-shaped opening 1003, the original center of the opening 1003 is irradiated. This is because the passing ion beam current is larger in FIG. 10B, which is shifted from FIG. 10A. Here, as a precondition, it is necessary to set the centers when the apertures are selected by the driving mechanism 126 of the projection mask 115 to be aligned. Thus, the irradiation position deviation can be corrected by correcting the irradiation ion beam position by adjusting the deflector 136 using a simple center-symmetric opening.

(c-4) Automatic correction 2
Maximizing the absolute value of the passing ion beam current I _b2 by ion beam deflection as described in (c-3) above is also a simple and effective adjustment method. As a more detailed adjustment method, ions irradiated on the mask are used. There is a method of correcting a deviation by acquiring a beam profile of a beam. This method will be described below with reference to FIG. First, the minute aperture 1101 is selected. It is better to select the minute opening (small hole) 1101 as small as possible under the condition that the passing ion beam current I _b2 can be monitored. This is because the hole diameter determines the resolution of the beam profile. Here, the minute circular aperture S is selected, and the passing ion beam monitored by the second Faraday cup 134 at this time is _defined as I _b2S . Here, a deflection scanning signal is applied by the deflector 136, and the ion beam applied to the projection mask 115 is deflected and scanned. A profile as shown in FIG. 11B can be obtained by using this deflection scanning signal and the I _b2S value of the ion beam current accompanying the application of the deflection scanning signal as an intensity signal. Incidentally, if the beam profile in the normal state is acquired in advance as shown in FIG. 11C and stored in the central processing unit 112, it can be compared with the abnormal state. FIGS. 11B and 11C show examples in which the voltage zero point of the deflector 136 (the state where the deflector 136 is not deflected) is used as the origin. Incidentally, in use (before the occurrence of an abnormality), a voltage is often applied to the deflector 136 in order to adjust the ion beam axis. For simplicity, this voltage is set to (Vx ₀ , Vy ₀ ) taking biaxial deflection as an example. Here, the central processing unit 112 evaluates and corrects the beam profile at the time of abnormality. As a correction means, the determination is made based on the deviation amount of the center of the beam profile, for example, the center of gravity of the current intensity. If the gravity center position of the current intensity at the time of abnormality is (Vxa, Vya), if (Vxa, Vya) is applied to the deflector 136 (that is, if it is shifted by (Vxa-Vx ₀ , Vya-Vy ₀ )) It becomes possible to adjust the beam to the optimum irradiation position. When evaluating in more detail, for example, the comparison of the peak current value at the normal time and the peak current value at the time of abnormality in the profile, the shape of the beam profile, that is, the region of a certain amount of current or more, for example, 13.5% or more of the peak current The evaluation can be made by comparing the shape and area of the region between normal and abnormal. In other words, if the irradiation ion beam is only shifted, these peak values and profile shapes should not change so much, but if these change greatly, it can be determined that it cannot be handled only by correction by beam shift. This is because it becomes possible. If it is determined that this method cannot be corrected, (c-1), (c-2), etc. are dealt with.

  As described above, according to the configuration of the present embodiment, by monitoring the currents of the two Faraday cups, the cause of the abnormality can be isolated and the abnormality can be corrected. It becomes possible to use it stably. Also, as shown in FIG. 12, just displaying two current values on the screen in the display window 1201 so that the user can monitor is effective because it helps the user to isolate the cause.

The above describes the case where normality and abnormality are separated based on the normal use range set in advance. However, other cases may be divided based on the rate of change. In particular, since the first Faraday cup current I _b1 can always be monitored except for the machining time, the change in I _b1 with respect to time is stored as shown in FIG. If the absolute value of the rate of change is greater than a certain threshold 1301 as may be sudden state change is determined to be abnormal as happened t _1.

  As a modification of the present embodiment, FIG. 14 shows an example of a combined apparatus of a scanning electron microscope (hereinafter referred to as SEM) to which the ion beam processing apparatus of FIG. 1 is applied and an ion beam processing apparatus. This composite apparatus has an ion beam optical system 105 and an electron beam optical system 1401 provided on a vacuum vessel 114, and can detect and observe a defective portion or the like of the sample 101 by the SEM function. The electron beam optical system 1401 is controlled by an electron beam optical system controller 1406. Here, the reason for performing the inspection using the electron beam 1402 is that, unlike the ion beam, the inspection sample wafer is not damaged, and the current apparatus generally has a higher resolution than the ion beam.

  About the place where the inside of the sample is to be observed in the defective portion detected in this way, the ion beam optical system 105 is used to process the sample by the cross section processing or the micro sample piece extraction method such as the micro sampling method. Here, an example is shown in which the ion beam optical system 105 is tilted so that the sample can be extracted even on a non-tilted sample stage.

  In the configuration example shown in FIG. 14, the electron beam optical system 1401 and the ion beam optical system 105 are configured to irradiate beams at different positions. That is, it is necessary to move the sample stage 102 in order to irradiate the beam at the same position in the sample. However, in this configuration, since the electron beam optical system 1401 and the ion beam optical system 105 do not mechanically interfere with each other, the distance from each optical system exit to the sample can be shortened. As a result, it is easy to increase resolution and increase current. On the other hand, although not shown in the figure, a configuration in which an electron beam and an ion beam can be applied to the same point may be employed. In this case, in order to avoid mechanical interference between the optical systems, it is necessary to make the tip of the optical system thinner, but there is an advantage that the ion beam processing portion can be observed on the spot using an electron beam.

  Reference numerals 101 to 136 in FIG. 14 are the same as the reference numerals of FIG. 1, and the description thereof is omitted here. The assist gas source 1403 supplies assist gas used for electron beam assist deposition or electron beam assist etching. A height sensor 1405 that measures the height of the sample 101 is controlled by a height sensor control device 1404.

  Thus, the position coordinates of the defective portion detected using the electron beam 1402 are sent from the stage position control device 103 to the central processing unit 112 and stored therein. However, in recent devices where miniaturization is progressing, it is difficult to specify the position to be processed only by the absolute accuracy of the stage because the accuracy required for the position to be analyzed for defects is submicron or less. For this reason, for example, an assist deposition gas is supplied from an assist gas source 1403, an electron beam 1402 is irradiated in the vicinity of the defective portion, and marking is performed with the electron beam assist deposition film, thereby forming a mark for accurately identifying the defective position. Keep it. Then, an SEM image including a defective portion and a mark is acquired and sent to the central processing unit 112 for storage. By doing so, the detected defective portion can be processed and analyzed with the ion beam. That is, the sample stage 102 is moved by the control of the stage position control device 103 to the position coordinates of the defective portion recorded in the central processing unit 112 so that the detected defective portion comes to the irradiation position of the ion beam 104. Although it depends on the stage position accuracy, in general, this stage movement causes a defective portion, that is, a mark by the electron beam assist deposition to enter the ion beam scanning region. Here, the SIM image is acquired and compared with the SEM image previously recorded in the central processing unit 112, whereby the defective portion to be processed can be specified from the mark position, and the failure analysis becomes possible. Thus, it is possible to easily realize from defect detection to defect analysis.

  As described above, since the apparatus shown in FIG. 14 can consistently analyze the detected defective portion on the spot in the same apparatus, it is possible to analyze the defect in a short time. Furthermore, by using ions that do not contaminate the sample, such as oxygen, nitrogen, or argon, in the ion beam used for processing, it is possible to perform from inspection to analysis without contaminating the sample wafer. You can also return to the process line. In the case of this apparatus, since the inspection time by the electron beam 1402 often occupies half or more of the apparatus operating time, the ion beam optical system 105 is often in a standby state. However, if the ion source is stopped in the standby state, the ion beam stability at the time of restarting is deteriorated, so that it is desirable to always operate the ion source. For this reason, as described above, it is very difficult to monitor the stability of the ion beam current with the first Faraday cup 130 by turning on the first blanker 128 so as not to damage the projection mask 115 during this waiting time. It is effective.

  In the above, the ion beam embodiment has been described. However, the beam adjustment for the mask used in the electron beam drawing apparatus or the like can be made with the electron beam.

  By using the ion beam processing apparatus described in the present embodiment, an ion beam abnormality can be detected, the cause can be identified, the abnormality can be corrected, etc., so that processing failure can be suppressed and stable processing can be realized. .

In this embodiment, an ion beam processing apparatus for realizing detailed management of the projection mask lifetime according to the present invention will be described.

ここで、dmは投射マスクの密度、Wmは投射マスク構成元素の原子量、Dmは投射マスクの厚さ(開口部の厚さ)である。Smは投射マスクのスパッタ率で、これは照射イオンビームのイオン種、投射マスクへの照射イオンエネルギー、投射マスク構成材料で決まる。Amは投射マスクへのイオンビーム照射面積であり、例えば実施例１で図１１を用いて説明したイオンビームプロファイル等からも求めることが可能である。Kは補正係数であり、ここでは特に開口のエッジ効果によるスパッタ増速の影響を補正するものであり、一般的には１よりも小さい値である。例えば0.5等になる場合も有る。 As described in the first embodiment, the projection mask 115 is a component having a short life in the apparatus. For this reason, it is one method to replace the ion beam current after abnormality occurs as in the first embodiment. However, it is possible to estimate the lifetime and replace it with a margin to prevent a processing failure and to stably operate the apparatus. It is effective to operate. However, there is a problem that the life is shortened if this allowance is taken too much. For this reason, it is important to estimate the life as accurately as possible. In the first embodiment, the relationship between the irradiation ion beam I _b2 to the sample and the sample processing has been described in (Equation 4), but the same argument holds for the projection mask 115 as well. That is, (Expression 5) is established as an expression of the projection mask lifetime tm.

Here, dm is the density of the projection mask, Wm is the atomic weight of the projection mask constituent element, and Dm is the thickness of the projection mask (thickness of the opening). Sm is the sputtering rate of the projection mask, which is determined by the ion species of the irradiation ion beam, the irradiation ion energy to the projection mask, and the projection mask constituent material. Am is the ion beam irradiation area to the projection mask, and can be obtained from, for example, the ion beam profile described with reference to FIG. K is a correction coefficient, which is used to correct the influence of sputter acceleration caused by the edge effect of the opening, and is generally a value smaller than 1. For example, it may be 0.5.

The edge effect of the opening will be described below with reference to FIG. The edge of the opening 1501 has a cross section as shown in FIG. 15A as an initial state, and if there is no edge effect, it should be processed as a damaged portion 1503 in FIG. However, in actuality, as shown in FIG. 15C, the amount of sputtering of the edge portion 1504 becomes larger. This is due to the fact that the sputtering rate is larger when it is inclined than when it is perpendicularly incident on the processing surface, and this is because the processing of the once-inclined opening edge portion is accelerated. . This acceleration effect can be corrected by the correction coefficient K. If the above numerical values are set, the lifetime can be determined by the current I _b1 of the first Faraday cup. However, this time tm calculated by the central processing unit is the lifetime for a certain opening. The actual use time ta of the aperture is the ion beam irradiation time during which the aperture is selected by the projection mask drive mechanism 126 and the first blanker 128 is turned off within the operation time of the ion beam optical system 105. This is managed by the central processing unit 112. In other words, the usage time ta can be used for a time shorter than the time tm. Actually, a margin is taken. For example, when a margin of 20% is taken, when the usage time ta reaches about 0.8 times tm, the central processing unit 112 comes to the display device 113 to replace the projection mask 115. By displaying this, it is possible to notify the user. In general, the lifetime is reached when any one of the openings reaches the above-mentioned life condition. However, as described in the first embodiment, when the projection mask 115 has a plurality of openings having the same shape, the opening that has reached the life condition. The use is prohibited, and continuous use becomes possible by using an alternative opening.

  The above-described life condition derivation is calculated based on the irradiation beam current value to the projection mask 115 and is therefore very effective for simply estimating the life, but a method for monitoring the state of the projection mask opening in more detail. Is described below. As shown in FIG. 16, this ion beam optical system has an ion source limiting mask 1601 on the ion source side of the projection lens 115. Although not shown in the figure, it has a large opening for passing a high-current ion beam for sample processing, and a minute opening for suppressing geometric aberration of the ion beam for sample observation and fine processing, The opening can be selected by a driving mechanism (not shown) of the ion source limiting mask. Here, a minute opening 1602 is selected to monitor the opening shape of the projection mask 115. Here, for example, it is assumed that an opening having a diameter of 10 μm is selected. Next, the irradiation lens 120 voltage is set under the condition that the opening of the ion source restriction mask 1601 is projected onto the projection mask 115. If the projection magnification of the irradiation lens 120 at this time is Mc, the ion beam is irradiated onto the projection mask 115 with a beam diameter of a size obtained by multiplying Mc by 10 μm. Here, the ion beam 1603 is deflected and scanned by the deflector 136.

A passing current profile of the opening 1604 can be obtained as shown in FIG. 17A, for example, using the second Faraday cup 134 current I _b2 at this time as an intensity signal. That is, this is an image binarized by the edge of the opening 1604, and a region 1701 where the ion beam passes through the opening is observed brightly, and a region 1702 which is shielded by the projection mask and does not pass the ion beam is observed darkly. Here, damage to the edge of the opening 1604 can be confirmed by comparing with the opening passing current profile in the initial state of the projection mask previously recorded in the central processing unit 112 (FIG. 17B). For example, FIG. 17A shows a region where the abnormal shape 1703 is damaged and the opening pattern is deformed, and it can be recognized that the lifetime has come. Also, as shown in FIG. 17C, when the region 1705 is observed larger than the normal region 1704, it is a case where the opening size is increased as a whole due to damage, and can be recognized as a lifetime.

ここで、Ieはイオンビーム照射により投射マスクから放出される二次電子電流である。即ち、(数６)から二次電子電流Ieは(数７)で表される。

このため図１６で説明したとおり、イオンビーム制限マスク１６０１の微小開口１６０２を照射レンズ１２０により投射マス１１５ク上に投射する条件で、偏向器１３６でイオンビーム１６０３を偏向走査し、予め測定しておいた第１のファラデーカップ電流I_b1と、偏向走査に伴う第２のファラデーカップ電流I_b2と投射マスク流入電流Imをモニタすることにより、中央処理装置１１２で(数７)の演算を行うことで、投射マスク１１５の二次電子像を図１９のように得ることができる。この像は二次電子の放出のしやすさが画像化されるため、開口部は領域１９０１のように暗く、それ以外の領域１９０２等はそれよりも明るく観察される。また、例えば開口エッジが斜面に削れている領域１９０３は明るく観察され、または汚染物(コンタミ)が形成された領域１９０４等は暗く観察される等、図１７と異なり開口周りのより詳細な情報を得ることができる。また、損傷領域１９０５を観察することで、イオンビームが開口に対してどのように照射されていたかが分かり、照射位置ずれ等も認識することができる。 The aperture monitor described with reference to FIG. 16 is a method capable of monitoring the aperture edge. However, in order to obtain more detailed information on the aperture of the projection mask 115, the configuration shown in FIG. A significant difference from FIG. 18 is that an ammeter 1801 is connected to the projection mask 115 and an inflow current can be measured. Here, the projection mask inflow current Im is expressed by the following (Equation 6).

Here, Ie is a secondary electron current emitted from the projection mask by ion beam irradiation. That is, from (Expression 6), the secondary electron current Ie is expressed by (Expression 7).

Therefore, as described with reference to FIG. 16, the ion beam 1603 is deflected and scanned by the deflector 136 under the condition that the minute aperture 1602 of the ion beam limiting mask 1601 is projected onto the projection mass 115 by the irradiation lens 120 and measured in advance. The central processing unit 112 performs the calculation of (Equation 7) by monitoring the first Faraday cup current I _b1 , the second Faraday cup current I _b2 associated with the deflection scan, and the projection mask inflow current Im. Thus, a secondary electron image of the projection mask 115 can be obtained as shown in FIG. In this image, since the ease of secondary electron emission is imaged, the opening is dark as in a region 1901 and the other regions 1902 and the like are observed brighter. Further, unlike FIG. 17, for example, a region 1903 in which the opening edge is cut into a slope is observed brightly, or a region 1904 in which contaminants (contamination) are formed is observed in darkness. Obtainable. Further, by observing the damaged region 1905, it is possible to know how the ion beam is applied to the aperture and to recognize an irradiation position shift or the like.

  By using the ion beam processing apparatus having the ion beam optical system described in the present embodiment, it is possible to grasp more detailed projection mask damage, so that processing failure due to projection mask damage is suppressed and stable processing is performed. Can be realized.

  In this embodiment, an FIB apparatus that realizes ion beam abnormality detection according to the present invention will be described.

  In the first and second embodiments, the example of the PJIB has been described. However, similar ion beam detection can be realized by the FIB. The FIB apparatus shown in FIG. 20 has a movable sample stage 2102 for placing a sample substrate of a sample 2101 such as a semiconductor wafer, and a sample position control for controlling the position of the sample stage 2102 in order to specify the observation and processing position of the sample 2101. An apparatus 2103, an ion beam optical system 2105 that performs processing by irradiating the sample 2101 with the ion beam 2104, and a secondary electron detector 2106 that detects secondary electrons from the sample 2101 are included. The secondary electron detector 2106 is controlled by a secondary electron detector controller 2107. An assist gas source 2108 for supplying an assist gas used for ion beam assist deposition or ion beam assist etching is controlled by a gas source controller 2109. A probe 2110 for extracting a processed sample and measuring electrical characteristics is controlled by a probe controller 2111. The central processing unit 2112 controls the secondary electron detector control device 2107, the gas source control device 2109, the sample position control device 2103, the probe control device 2110, and the control devices of each component of the ion beam optical system 2105 described later. Is done. For example, a personal computer or a workstation is generally used as the central processing unit 2112 here. In addition, the display device 2113 is included. A sample stage 2102, an ion beam optical system 2105, a secondary electron detector 2106, an assist gas source 2108, and the like are arranged in a vacuum vessel 2114. With this configuration, the ion beam 2104 formed by the ion beam optical system 2105 is irradiated to the sample 2101 placed on the sample stage 2102 for processing.

  Next, details of the ion beam optical system 2105 will be described. The ion source 2116 generates ions and is controlled by the ion source controller 2117. In this embodiment, the case of a plasma ion source is shown. As the plasma ion source, various ion sources such as a duoplasmatron, an inductively coupled plasma ion source, a Penning ion source, and a multicusp ion source can be used. These plasma ion sources are mainly used as ion sources for gas materials such as oxygen, nitrogen, and rare gases. In addition to the plasma ion source, an ionization ion source or the like is also used as an ion source for the gas material. In addition, a liquid metal ion source or the like is also used as an ion source of a material such as a metal, and various ion sources can be used in this apparatus. Ions are extracted as an ion beam through an extraction electrode 2118. The extracted ion beam is focused on the sample 2101 by a focusing lens 2120 controlled by a focusing lens power source 2119 and an objective lens 2122 controlled by an objective lens power source 2121.

  That is, in this FIB configuration, the focusing lens 2120, the objective lens 2120, the objective lens 2120, and the objective lens 2122 are focused on the point where the ion beam is most focused on the sample in two stages. A lens 2122 is used. Incidentally, the point where the ion beam is most focused is, for example, an opening of an anode in the case of a plasma ion source or the like, and an opening of an ion source restriction mask in the example described in the second embodiment. In the case of an ionization ion source, the ion emission point. In the case of a plasma ion source, in addition to the image formation by the two-stage lens of the focusing lens and the objective lens as described above, the cross point of the ion beam formed by the focusing lens 2120 is connected to the sample by the objective lens 2122. There is also a way to image.

  Also, the major difference from PJIB is that the processed shape of the sample is not determined by the shape of the projection mask opening, but the ion beam focused on the spot on the sample as described above is controlled by the main deflector controller 2123. The point is that the ion beam irradiation position is determined and processed by performing deflection scanning with the deflector 2124. For this reason, it is possible to process an arbitrary shape. In this FIB apparatus, a beam limiting aperture 2115 formed of a plate-shaped member having an aperture is used to determine an ion beam spot diameter and an ion beam current value on the sample. That is, a plurality of apertures of different circular sizes are usually provided and switched by the beam limiting aperture drive mechanism 2126 controlled by the beam limiting aperture control device 2125. However, since the beam diameter is large at a large aperture, the processing accuracy is poor. Various processing such as high-speed machining using a large current and low-speed machining due to a small current at a small opening, but high-precision machining due to the narrow beam diameter can be realized. Further, scanning is performed by the main deflector 2124, secondary electrons generated by the scanning are detected by the secondary electron detector 2106, and this is imaged on the display device 2113 as a contrast signal, whereby the SIM on the surface of the sample 2101 is detected. An image can be acquired.

  Here, as shown in FIG. 20, the first blanker 2128 and the first Faraday cup ammeter controlled by the first blanker controller 2127 above the beam limiting aperture 2115 as in the first and second embodiments. A first Faraday cup 2130 to which 2129 is connected, a second blanker 2132 controlled by a second blanker controller 2131 and a second Faraday cup 2134 to which a second Faraday cup ammeter 2133 is connected. It has the composition to have. Further, a deflector 2136 controlled by a deflector control device 2135 is provided on the beam limiting aperture 2115. In this way, since the ion beam currents above and below the beam limiting aperture 2115 can be monitored, the same effect as the abnormality detection shown in the first and second embodiments can be obtained by the FIB.

  By using the ion beam processing apparatus described in this embodiment, an ion beam abnormality can be detected even in FIB, and the cause can be identified and corrected, so that processing failure can be suppressed and stable processing can be realized. Can do.

  Further, although the ion beam embodiment has been described above, the same effect can be obtained with other charged particle beam devices such as an SEM because the beam can be adjusted with respect to the aperture by the electron beam.

  As described above, since the present invention is effective for inspection and analysis of semiconductor processes, it can be used to improve yields at semiconductor manufacturers and can greatly contribute to cost reduction.

The figure which shows the structural example of the PJIB apparatus by the 1st Example of this invention. The figure which shows the Faraday cup and blanker of a 1st Example. The figure which shows the operation example of the two-step blanker and Faraday cup of a 1st Example. The figure which shows the example of the processing flow of a 1st Example. The figure which shows the example of the abnormality display of a 1st Example. The figure which shows the corresponding manual display example of a 1st Example. The figure which shows the structural example of the duoplasmatron of a 1st Example. The figure for demonstrating the ion beam irradiation shift | offset | difference to the projection mask of a 1st Example. The figure which shows the example of the opening of center symmetry of a 1st Example. The figure which shows the example of ion beam irradiation with the opening which is not centrally symmetric of a 1st Example. The figure which shows the example of the acquisition method of the ion beam profile of a 1st Example. The figure which shows the example of a display of the ion beam monitor value of two places of a 1st Example. The figure which shows the example of the time change of the ion beam monitor current in a 1st Example. The figure which shows the structural example of the PJIB-SEM composite apparatus as a modification of a 1st Example. The figure which shows the example of the sputter | spatter damage of the projection mask opening edge for demonstrating the 2nd Example of this invention. The figure which shows the structural example of the projection mask shape monitor in a 2nd Example. The figure which shows the example of the projection mask aperture passage current profile by the 2nd Example. The figure which shows the structural example of the secondary electron monitor of the projection mask shape by a 2nd Example. The figure which shows the example of the projection mask secondary electron image by a 2nd Example. The figure which shows the structural example of the FIB apparatus which is the 3rd Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Sample, 102 ... Sample stand, 103 ... Sample position control apparatus, 104 ... Ion beam, 105 ... Ion beam optical system, 106 ... Secondary electron detector, 107 ... Secondary electron detector control apparatus, 108 ... Assist gas 109, gas source control device, 110 ... probe, 111 ... probe control device, 112 ... central processing unit, 113 ... display device, 114 ... vacuum vessel, 115 ... projection mask, 116 ... ion source, 117 ... ion source control 118: Extraction electrode, 119 ... Irradiation lens power supply, 120 ... Irradiation lens, 121 ... Projection lens power supply, 122 ... Projection lens, 123 ... Main deflector control device, 124 ... Main deflector, 125 ... Projection mask control device, 126 ... projection mask drive mechanism, 127 ... first blanker control device, 128 ... first blanker, 129 ... first Faraday 130 ... first Faraday cup 131 ... second blanker control device 132 ... second blanker 133 ... second Faraday cup ammeter 134 ... second Faraday cup 135 ... Deflector control device, 136 ... Deflector, 201 ... Faraday cup, 202 ... Secondary electron, 203 ... Ion beam, 204 ... Ammeter, 205 ... Faraday cup, 206 ... Micro hole, 207 ... Blanker, 208 ... Ammeter, 501 ... Display, 502 ... Schematic configuration of device, 503 ... Area, 601 ... Correspondence flow, 602 ... Question, 603 ... Button, 701 ... Cathode, 702 ... Intermediate electrode, 703 ... Magnet, 704 ... Anode, 705 ... Control electrode, 801... Opening, 802... Irradiation beam, 901 to 905... Opening, 1001... Irradiation ion beam, 1002. DESCRIPTION OF SYMBOLS 03 ... Aperture, 1101 ... Minute aperture, 1201 ... Display window, 1301 ... Threshold, 1401 ... Electron beam optical system, 1402 ... Electron beam, 1403 ... Assist gas source, 1404 ... Height sensor controller, 1405 ... Height sensor, DESCRIPTION OF SYMBOLS 1406 ... Electron beam optical system control apparatus, 1501 ... Aperture, 1502 ... Ion beam, 1503 ... Damaged part, 1504 ... Edge part, 1601 ... Ion beam source mask, 1602 ... Aperture, 1603 ... Ion beam, 1604 ... Aperture, 1701, 1702 ... Area, 1703 ... Abnormal shape, 1704, 1705 ... Area, 1801 ... Ammeter, 1901, 1902, 1903, 1904 ... Area, 1905 ... Damaged area, 2101 ... Sample, 2102 ... Sample stage, 2103 ... Sample position control device 2104 ... Ion beam 2105 ... Ion beam optical system 2106 ... Secondary electron detector, 2107 ... Secondary electron detector control device, 2108 ... Assist gas source, 2109 ... Gas source control device, 2110 ... Probe, 2111 ... Probe control device, 2112 ... Central processing unit, 2113 ... Display device, 2114 ... vacuum vessel, 2115 ... beam limiting aperture, 2116 ... ion source, 2117 ... ion source control device, 2118 ... extraction electrode, 2119 ... irradiation lens power supply, 2120 ... irradiation lens power, 2121 ... objective lens power supply, 2122 ... Objective lens, 2123 ... main deflector control device, 2124 ... main deflector, 2125 ... beam limiting aperture control device, 2126 ... beam limiting aperture drive mechanism, 2127 ... first blanker control device, 2128 ... first blanker, 2129 ... 1st Faraday cup ammeter, 2130 ... 1st Faraday cup , 2131 ... second blanker system controller, 2132 ... second blanker, 2133 ... second Faraday cup ammeter, 2134 ... second Faraday cup, 2135 ... deflector controller, 2136 ... deflector.

Claims (18)

A sample stage for holding a sample, an ion source for generating an ion beam, a plate-like member having an opening, and an irradiation optical system for irradiating the sample held on the sample stage with an ion beam transmitted through the opening In an ion beam processing apparatus having
A blanker and a beam current detector are provided on the ion source side of the plate-like member, and the current is monitored by the beam current detector by turning on the blanker when irradiation of the ion beam to the sample is unnecessary. Ion beam processing equipment. The ion beam processing apparatus according to claim 1,
The ion beam processing apparatus, wherein the plate-like member having the opening is a projection mask having a pattern opening. The ion beam processing apparatus according to claim 1,
A display device;
An ion beam processing apparatus, wherein when the current of the beam current detector fluctuates beyond a preset current value range, a display indicating abnormality or a countermeasure manual is displayed on the display device. The ion beam processing apparatus according to claim 1,
The ion beam processing apparatus, wherein the beam current detector is a Faraday cup. In an ion beam processing apparatus having a sample stage for holding a sample, an ion source for generating an ion beam, a plate-like member having an opening, and an irradiation optical system for irradiating the ion beam transmitted through the opening to the sample ,
An ion beam comprising: a first blanker and a first beam current detector on the ion source side of the opening; and a second blanker and a second beam current detector on the sample side of the opening. Processing equipment. In the ion beam processing apparatus according to claim 5,
When the irradiation of the ion beam to the sample is unnecessary, the first blanker is turned on, the current is monitored by the first beam current detector, and the first blanker is immediately before irradiation of the ion beam to the sample. Is turned off, the second blanker is turned on, and the current is monitored by the second beam current detector. The ion beam processing apparatus according to claim 5 or 6,
The ion beam processing apparatus, wherein the plate-like member having the opening is a projection mask having a plurality of pattern openings. In the ion beam processing apparatus according to claim 7,
An ion beam processing apparatus further comprising a display device, wherein the current value of the first beam current detector and the current value of the second beam current detector are displayed on the display device. The ion beam processing apparatus according to claim 8, wherein
By comparing the time calculated from the current value of the first beam current detector and the ion beam irradiation time to the pattern opening, the replacement timing of the projection mask is displayed on the display device. Ion beam processing equipment. The ion beam processing apparatus according to claim 8, wherein
An ion beam processing apparatus, wherein when the current of the first beam current detector fluctuates beyond a preset current value range, a display indicating abnormality or a countermeasure manual is displayed on the display device. The ion beam processing apparatus according to claim 8, wherein
When the current of the first beam current detector is within a preset current value range and the current of the second beam current detector is larger than the preset current value, the display device is provided with the projection mask. An ion beam processing apparatus characterized by displaying a display indicating an abnormality or a countermeasure manual. In the ion beam processing apparatus according to claim 7,
Both the first blanker and the second blanker are turned off only for a time calculated from the current value of the second beam current detector and the opening area of the pattern opening registered in advance. apparatus. In the ion beam processing apparatus according to claim 7,
A deflector disposed on the ion source side of the projection mask;
When the current of the first beam current detector is within a preset current value range and the current of the second beam current detector is smaller than the preset current value, the second beam current detector The ion beam machining apparatus is characterized in that the deflector is set to a beam deflection condition in which the current of the current falls within the preset current value range. In the ion beam processing apparatus according to claim 7,
The projection mask has micro holes formed therein, and a deflector disposed on the ion source side of the projection mask, the plurality of pattern openings and the micro holes provided in the projection mask under the ion beam irradiation region. A mask drive mechanism for selectively switching, and the mask drive mechanism selectively switches the minute hole under the ion beam irradiation region and applies a deflection scanning signal to the deflector to deflect and scan the ion beam. An ion beam processing apparatus that acquires a beam profile of the ion beam from a current value of the second beam current detector and the deflection scanning signal. The ion beam processing apparatus according to claim 14, wherein
When the current of the first beam current detector is within a preset current value range and the current of the second beam current detector is smaller than the preset current value, the maximum current region of the beam profile is An ion beam processing apparatus, wherein the deflector is set to a beam deflection condition that is a position of the minute hole. The ion beam processing apparatus according to claim 5 or 6,
The ion beam processing apparatus, wherein the first and second beam current detectors are Faraday cups. In the ion beam processing apparatus according to claim 5 or 6,
An ion beam processing apparatus comprising: an output unit that outputs abnormality information when the current of the first beam current detector fluctuates beyond a preset current value range. The ion beam processing apparatus according to claim 5 or 6,
When the current of the first beam current detector is within a preset current value range and the current of the second beam current detector is larger than the preset current value, an output unit that outputs abnormality information is provided. An ion beam processing apparatus comprising:

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